SMS:Map Module

At a glance

Map Module
Map
Feature Objects
Coverages
More
Map Module Interface
Map Display Options
Map Module Tools
Feature Objects Menu
Map Project Explorer

• Create and edit GIS like data
• Used to create conceptual models as well as data for other purposes
• Conceptual model is a geometry (mesh/grid) independent representation of the numeric model domain and/or boundary conditions
• Conceptual models can be converted to model geometry and boundary conditions
• Conceptual model makes it easier to create, edit, and alter models

The Map module provides tools for creating, managing and editing feature objects. Feature objects are geometric entities, meaning they have a defined position or shape, and the attributes associated with those entities. The simplest feature object is a feature point, which defines a single location. Increasing in complexity, the next GIS object is an arc, which defines a line or polyline. Areas enclosed by polylines can be classified as a feature polygon.

Feature objects with related attributes are grouped into layers or coverages. The coverage definition includes a "type" that determines the attributes available for the objects in the coverage. See the list of coverage types to learn about the attributes associated with objects in that specific coverage.

The principal application of coverages in the SMS is to facilitate the representation of a numerical simulation in a representation that is independent of a specific discretization (a specific set of nodes and elements or cells). This allows the modeler to interact with a much smaller set of entities and reduces redundant effort in the modeling process.

A secondary application of coverages is to define geometric objects for data extraction from numerical model results.

Conceptual Model

A conceptual model is a high level representation used to define attributes used in the Mesh or Cartesian Grid generation process such as:

• Bathymetry source
• Materials information
• Boundary conditions

Creating Feature Objects

Feature objects are the building blocks of a conceptual model. They define the geometric shapes, locations and extents of objects in the model. There are several mechanisms for creating feature objects including:

• Extracting feature arcs from the contours of a scatter set. See Scatter Contour to Feature for more information.
• Importing from a web data source such as a coastline database. See Import from Web for more information.
• Importing from CAD data.
• Interactive definition (digitizing) using the Map Module Tools.
• Creation as a stamped feature to define built up embankment or dredged channels.

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Elevations of Feature Objects

In the map module, Nodes, vertices and arcs all have an elevation attribute. That means that you can assign an elevation to individual nodes, points or vertices, or you can assign it to the arc. If you assign an elevation to an arc, the attribute of the nodes and vertices in that arc are updated as well. This will override any z-value specified for individual vertices or nodes on the arc.

The elevations of the map objects can also be assigned using the interpolation from the scatter module. In this case, each object (node, point, vertex, and arc) are assigned an elevation (z-value) based on the scatter set. The location for interpolation of the arc is the mid-point of the arc.

When you digitize in the map module, elevations are assigned as with other digitization in SMS. That means that when you create a node, point, or vertex, it is assigned the default elevation value for digitization. The default elevation is initialized to 0.0. The default changes any time you specify a Z-value. Therefore, if you create a map point or node, and specify an elevation for that selected point, the value you specify is now the default value for newly digitized points, nodes and vertices. (Note: when you create mesh nodes, there is an option to ask for an elevation each time you create a node, but this option is not available for scatter vertices or map module objects.)

When you convert a map coverage to a scattered data set, you have the option of using the arc elevations or the node and vertex elevations for the new scatter set. (There is also an option to use the arc spacing, but that is for a different purpose. It is not an elevation, but is useful sometimes as a function on a scattered data set.)